The present invention relates to new transition metal complex compounds with
octaethyl porphyrin or
5,10,15,20-tetraphenyl porphyrins or
5,10,15,20-tetra(4-pyridyl)-porphyrins as ligands
which optionally carry an anion on the central atom and are suitable as catalysts for the epoxidation of olefins with hydrogen peroxide.
Olefin oxides (oxiranes) are compounds of considerable industrial significance. They are used in the area of varnishes, for the preparation of polyethers, polyurethanes, epoxide resins, detergents, glycols and a plurality of organic intermediate products (cf. U.S. Pat. No. 2,412,136 and DE-AS 11 39 477).
Various methods are already known for the epoxidation of olefins. Thus, oxiranes can be prepared according to the chlorohydrin method by reacting olefins with chlorine or sodium hypochlorite in alkaline medium and by a subsequent treatment with bases.
A further known process is based on the reaction of olefins with organic hydroperoxides in the presence of a catalyst (cf. DE-AS 14 68 012).
A further known method is based on the use of organic peracids obtained by oxidation in air of the corresponding aldehydes or from carboxylic acids with hydrogen peroxide (cf. BE-PS 535 068).
Disadvantages associated therewith can be eliminated by using hydrogen peroxide as epoxidation agent since in this instance, according to theory, only water should be formed along with the epoxidation product. Since the reactivity of hydrogen peroxide is weak in relation to olefins, epoxidations with this reagent are carried out with the use of catalysts. Catalysts such as molybdenum compounds and tungsten compounds are suitable only for a few olefins. The following developments are noted in this connection, for example, GB 837,464, in which the various metal catalysts described in "J.A.C.S.", vol. 59, pp. 2342 to 2344, 1937 are used; U.S. Pat. No. 2,786,854, according to which tungstic acid is used; U.S. Pat. No. 2,833 787, according to which acidic salts of metals of group VI of the periodic system of the elements, e.g. of tungsten or molybdenum, are used; BE-PS 860,776, according to which compounds containing tungsten and containing molybdenum are used; U.S. Pat. No. 3,993,673, according to which catalysts containing arsenic are used; U.S. Pat. No. 3,953,362, according to which a catalyst containing molybdenum is used; U.S. Pat. No. 4,026,908, according to which mercury derivatives plus a compound with molybdenum, tungsten, vanadium or titanium is used; U.S. Pat. No. 3,806,467, according to which organic and inorganic tin compounds plus organic or inorganic compounds containing molybdenum, tungsten, vanadium, selenium or boron are used; "Bull. Chem. Soc. Jap." 42, pp. 1604, 1969, according to which selenium dioxide is used: and U.S. Pat. No. 3,778,451, according to which compounds with molybdenum, tungsten, vanadium, niobium, tantalum, uranium and rhenium are used.
These substances are catalytically active; however, the methods which can fundamentally be carried out with them have not found acceptance in the art for various reasons. In conjunction with hydrogen peroxide solutions, either the hydrogen peroxide is rapidly decomposed by them or only an unsatisfactory epoxidation speed of reaction is achieved. Methods using these catalysts tend also to be problematical to the extent that in addition to the desired epoxidation product, frequently rather large amounts of byproducts such as diols and ketones are formed, the separation of which can pose considerable problems.
Attempts have also been undertaken in the past to carry out methods for the catalytic epoxidation of olefins with other epoxidation agents using metal porphyrin complexes as catalysts. Metal catalysts which have been suggested as suitable for reaction with epoxidation means such as iodosobenzene, alkali metal hypochlorite as well as organic hydroperoxides are e.g. chloro-iron(III)-tetraphenyl porphyrin (FeCl) (TPP), chloro-manganese(III)-tetraphenyl porphyrin (MnCl) (TPP) or chloro-chromium(III)tetraphenyl porphyrin (CrCl) (TPP). Manganese(III)-tetraphenyl porphyrin has also already been used with hydrogen peroxide as oxidation agent (J.-P. Renaud; P. Battioni; J. F. Bartoli; D. Mansuy, "J. Chem. Soc., Chem. Commun.", 1985, 888). However, these catalysts exhibit a strong decomposing action on H.sub.2 O.sub.2, so that the selectivities which can be achieved regarding hydrogen peroxide are only very low unless expensively substituted porphyrin ligands are used.
Oxo-metal porphyrin complexes such as oxochloro(5,10,15,20-tetraphenyl porphyrinato)-molybdenum (v) (O.dbd.Mo (TPP) Cl) have also already been suggested in combination with organic hydroperoxides. However, an attempt to use hydrogen peroxide with a catalyst of the composition methoxo-oxo(5,10,15,20-tetraphenyl porphyrin)-molybdenum(v) for epoxidizing the olefin cyclohexene instead of an organic hydroperoxide failed: No epoxidation was able to be observed (F. Varescon, Thesis, Claude Bernard University, Lyons I, 1982).